ath9k: fix storage endpoint lookup

Make sure to use the current alternate setting when verifying the
storage interface descriptors to avoid submitting an URB to an invalid
endpoint.

Failing to do so could cause the driver to misbehave or trigger a WARN()
in usb_submit_urb() that kernels with panic_on_warn set would choke on.

Fixes: 36bcce43 ("ath9k_htc: Handle storage devices")
Cc: stable <stable@vger.kernel.org>     # 2.6.39
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath9k/hif_usb.c

@@ -1216,7 +1216,7 @@ static void ath9k_hif_usb_firmware_cb(const struct firmware *fw, void *context)
 static int send_eject_command(struct usb_interface *interface)
 {
 	struct usb_device *udev = interface_to_usbdev(interface);
-	struct usb_host_interface *iface_desc = &interface->altsetting[0];
+	struct usb_host_interface *iface_desc = interface->cur_altsetting;
 	struct usb_endpoint_descriptor *endpoint;
 	unsigned char *cmd;
 	u8 bulk_out_ep;